The present invention pertains to packaging for implantable prosthetic devices and in particular to leakproof packaging for prosthetic devices packaged in liquid media.
Prosthetic heart valves are representative of numerous implantable medical devices that must be stored for long periods of time in a sterile package or in sealed, anti-bacterial packaging. Often such packages contain a liquid, which may have antibacterial properties to inhibit transmission of disease with the implantable device. To effectively package a heart valve in a liquid storage medium, it is important to have a container that can be manipulated within a sterile environment such as a glove box. The assembled container should provide a seal that will inhibit the loss of the liquid storage medium for a substantial period of time, for example, for as long as five years. Despite the need for a reliable seal, however, it should not be difficult for operating room staff to open the container in the sterile and constrained circumstances of open-heart surgery, where it is anticipated that the present invention will be used.
Today, there are three major types of heart valves: mechanical valves, bioprosthetic or tissue valves, and polymer valves. The term xe2x80x9cmechanical valvexe2x80x9d as used herein, refers to a heart valve made exclusively of rigid synthetic materials and which comprises essentially no biological components. The term xe2x80x9cbioprosthetic valve,xe2x80x9d on the other hand, refers to a heart valve comprising at least some biological components such as tissue or tissue components (e.g., collagen). The biological components are obtained from a donor animal (typically bovine or porcine), and the valve may comprise either biological materials alone or biological materials with man-made supports or stents. Polymer valves, on the other hand, are heart valves made of at least some elastomeric polymer components, including specifically leaflet occluders made of elastomeric polymers. The present invention is suitable for use in connection with all three major types of heart valves.
Mechanical heart valves are generally characterized by a rigid annular valve body supporting one or more occluders, with a sewing ring or sewing cuff circumscribing the annular valve body. Pyrolytic carbon is a material often used for the valve body or the occluders, although other materials such as metal, polymers or ceramics have also been proposed. The sewing ring is often comprised of silicone rubber with a polymeric fabric cover (e.g., Dacron(trademark) fabric). A metal stiffening ring may be provided between the valve body and the sewing ring and a metal lock wire may be used to secure the stiffening ring and/or sewing ring to the valve body.
A bi-leaflet mechanical valve typically comprises an annular valve body in which two opposed leaflet occluders are pivotally mounted. Monoleaflet mechanical heart valves typically comprise a single leaflet occluder coupled to the annular valve body. Monoleaflet valves typically open by pivoting movement, although some valves open by a combination of pivoting and translational movement. For both bi-leaflet and monoleaflet mechanical valves, the occluders are typically substantially rigid, although some designs incorporate flexible leaflets. In bi-leaflet valves, the leaflets move between a closed position in which the two leaflets are mated to prevent blood flow in the reverse direction, and an open position in which the occluders are pivoted away from each other to permit blood flow in the forward direction. In monoleaflet valves, the leaflet pivots and/or translates from the closed to the open position to allow blood flow. In each case, however, the energy of blood flow causes the occluders to move between their open and closed positions.
Mechanical valves have also been made with flexible leaflets fabricated from man-made materials such as polyurethane, silicone rubber or other biocompatible polymer, for example, a valve described by Purdy, et al., U.S. Pat. No. 5,562,729, incorporated herein by reference. A sewing ring is provided for mounting flexible leaflet mechanical heart valves in a patient""s heart.
Bioprosthetic heart valves, in contrast to mechanical valves, comprise an annulus formed by an annular stent to which three flexible leaflets, comprised of a biological material such as bovine or porcine pericardium, are coupled. When blood flows in the forward direction, the energy of the blood flow deflects the leaflets away from the center of the annulus and allows blood to flow in the forward direction. When the pressure across the valve reverses and blood begins to flow in the reverse direction, the three leaflets engage each other in a coaptive region, occluding the valve body annulus and preventing the flow of blood through the valve in the reverse direction. The valve leaflets are made from tissue, such as specially treated porcine or bovine pericardial tissue.
Mechanical heart valves have usually been packaged in containers that support the mechanical valve in such a way as to protect or isolate it from mechanical shocks. Representative packaging patents include Cromie, U.S. Pat. No. 4,101,031; Lubock et al., U.S. Pat. No. 4,801,015; Dohm et al., U.S. Pat. No. 5,720,391; and Caudillo et al., U.S. Pat. No. 5,823,342, all of which are hereby incorporated herein by reference in their entirety. Mechanical valves are typically shipped and stored in a sterilized condition in airtight containers. Because mechanical valves do not comprise biological materials, air is used as the medium in the containers. Inclusion of a liquid storage medium, such as an antibacterial solution, has been deemed unnecessary at best, and possibly damaging to the structural materials during storage, and has been avoided on the basis of added cost as well as the risk of possible harm to the valve. However, Pathak and Chinn have suggested, in a co-pending application filed contemporaneously with the present Application, that liquids may also be advantageously used in mechanical heart valve packaging.
Bioprosthetic valves, on the other hand, are almost always shipped or stored in liquid media because of the need to maintain the biological components of the valve in a hydrated condition. In addition, the medium may have anti-bacterial properties or additives to ensure sterility and protect the biological components from bacterial degradation.
To effectively package a heart valvexe2x80x94whether mechanical or bioprostheticxe2x80x94in a liquid medium, it is important to have a container that can be manipulated within a sterile environment such as a glove box. The assembled container should provide a seal that will inhibit the loss of the liquid medium for a substantial period of time, for example, for as long as five years. In addition to the need for a reliable seal, however, the container should be easy for operating room staff to open in the sterile and constrained circumstances of open-heart surgery, where it is anticipated that the present invention will be used.
The present invention comprises packaging for an implantable prosthesis such as a heart valve, wherein the prosthesis is immersed in a liquid medium in the container, which may optionally have antibacterial properties. The packaging comprises ajar and a lid assembly having a seal and a ridge therebetween, the ridge being adapted to contact the seal. At least one circumferential leg is interposed between the lid assembly and the jar. The leg maintains a predetermined spacing between the lid and the jar and may be loaded in compression. The lid assembly may comprise a lid and an overcap. The overcap may turn independently of the lid and may apply compressive pressure to the lid over the ridge and seal. The lid and overcap may be coupled together by, for example, mating snap hooks. At least one of the lid or overcap may have a plurality of snap hooks. At least one of the plurality of snap hooks may be of a length different than the other snap hook(s), whereby an asymmetric force may be applied to the lid when the overcap is loosened from the jar.
It is an object of the invention to provide a package for an implantable prosthetic device comprising ajar and lid assembly, the lid assembly having a lid connected to an overcap.
Another object of the invention is to provide a package that is easily assembled in a sterile environment.
Yet another object of the invention is to provide a package that maintains a seal for long periods of time but wherein resistance or friction associated with opening the package is reduced.
A further object of the invention is to provide a package comprising ajar and lid assembly with a seal interposed between the jar and lid assembly.
Another object of the invention is to provide a structure whereby a pre-load between the lid assembly and the jar that is not supported by the seal to maintain loads on the seal within acceptable parameters.
A further feature of the invention is a pre-load structure comprising radially spaced annular legs adjacent an annular seal, the legs contacting an overcap and ajar and adapted to receive a compressive pre-load between the overcap and the jar.
It is also an object of the invention to provide a lid assembly comprising a lid and overcap that are rotatably connected.
Another feature of the invention is a lid and overcap that are connected by mating snap hooks.
Yet another feature of the invention is an arm structure on an overcap for applying compressive force through a lid to a seal.
These and other features and advantages of the invention will be apparent from the following description and accompanying drawings.